1. Field of the Invention
This invention relates to novel unsaturated peroxides, their use as free-radical generators for, (1) polymerizing ethylenically unsaturated monomers, (2) curing unsaturated polyester resins, (3) crosslinking olefin polymers, (4) preparing polymeric peroxides, (5) curing elastomeric compositions, (6) rheological modification of olefin polymers and copolymers, (7) grafting of ethylenically unsaturated monomers onto polymers, and (8) compatibilizing of polymer blends. Compounds and processes for their preparation as well as products and articles of manufacture produced by their use are also contemplated by the invention.
There is a need in the polymer industry for efficient, free-radical crosslinking agents for olefin polymers which give longer scorch times and yet provide faster crosslinking rates. Because of its low melt flow, HDPE must be compounded with peroxides at temperatures where the scorch time is relatively short. If the scorch time is too short, premature crosslinking of HDPE occurs during the peroxide compounding step. This is highly undesirable. In the crosslinking of high density polyethylene (HDPE), the peroxide that is predominantly used for crosslinking is 2,5-dimethyl-2,5-di-(t-butylperoxy)-3-hexyne (available as LUPERSOL.RTM. 130 from Elf Atochem North America, Inc.). Of all the commercially available organic peroxides, LUPERSOL 130 has the highest 10 hour half-life temperature (131.degree. C.). The 10 hour half-life temperature of an initiator is defined as the temperature at which 50% of the initiator decomposes in 10 hours. Generally, the higher the 10 hour half-life temperature the longer the scorch time at a given temperature.
Although LUPERSOL 130 gives adequate scorch times when compounded into HDPE, polymer producers complain of the noxious decomposition products that LUPERSOL 130 produces during crosslinking of polyethylene. The noxious decomposition products are thought to be derived from the carbon-carbon triple bond in LUPERSOL 130 since a similar peroxide that lacks the carbon-carbon triple bond, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, does not produce noxious decomposition products. An efficient polyethylene crosslinking agent which yields lengthened scorch times and produces less noxious decomposition products is needed by the polyethylene crosslinking industry.
A novel unsaturated peroxide of the instant invention, 1,3-dimethyl-3-(t-butylperoxy)butyl methacrylate, satisfied these crosslinking needs and was found to be a more effective HDPE crosslinking agent than was LUPERSOL 130. At 385.degree. F. (196.degree. C.) in HDPE, 1,3-dimethyl-3-(t-butylperoxy)butyl methacrylate was found to be at least as efficient as LUPERSOL 130 on an equivalent basis and was found to give faster crosslinking of HDPE than LUPERSOL 130. It also gave longer scorch times than LUPERSOL 130, hence, it is superior to LUPERSOL 130 for crosslinking of HDPE. Perhaps because of the lack of a carbon-carbon triple bond in the structure of 1,3-dimethyl-3-(t-butylperoxy)butyl methacrylate, generation of noxious decomposition products during crosslinking of polyethylene was not observed.
In recent years most of the new polymeric materials that have been commercialized are polymeric blends and alloys composed of two or more different polymers. The reasons for this trend to commercial development of polymer blends and alloys include the short time required for development and commercialization of these materials, the relatively low cost involved in carrying out the R&D effort needed to develop these materials compared to development of entirely new polymers from monomers, and the ability to develop polymeric blends and alloys that are "tailor made" to meet end use property specifications, hence, they are neither over-engineered nor under-engineered, but are just right. The polymer property improvements achieved by blending include:
Better processability PA1 Impact strength enhancement PA1 Improved flame retardance PA1 Improved barrier properties PA1 Improved tensile properties PA1 Improved adhesion PA1 Improved melt flow PA1 Enhanced heat distortion temperature (HDT) PA1 Enhanced heat resistance PA1 Improved stiffness PA1 Improved chemical resistance PA1 Improved ultraviolet light stability PA1 Q is an unsaturated diradical selected from structures (1), (2), or (3) ##STR7## where (X--R.sub.1) shows the point of attachment of the X--R.sub.1 group and (R) shows the point of attachment of the R group to the Q diradical; PA1 R is selected from the group consisting of H--, carboxy, alkoxycarbonyl radicals of 2 to 19 carbons, aryloxycarbonyl radicals of 7 to 15 carbons, t-alkylperoxycarbonyl radicals of 5 to 11 carbons, alkyl radicals of 1 to 18 carbons, alkenyl radicals of 2 to 18 carbons, aryl radicals of 6 to 10 carbons, and R.sub.1 --X-- radicals; PA1 R.sub.2 is selected from the group consisting of H-- and alkyl radicals of 1 to 4 carbons; PA1 R.sub.3 is selected from the group consisting of H--, alkyl radicals of 1 to 18 carbons and alkenyl radicals of 2 to 18 carbons provided that when R.sub.3 is methyl, R and R.sub.2 are not both hydrogen; PA1 R.sub.1 is a peroxy containing radical of structures (4), (5), and (6): ##STR8## where: t is 0 or 1; PA1 v is 1 or 2; PA1 w is 1 or 2; PA1 T is a direct bond or oxy; PA1 R.sub.4 is selected from the group consisting of t-alkyl radicals of 4 to 12 carbons, t-aralkyl radicals of 9 to 13 carbons and t-alkynyl radicals of 5 to 9 carbons; PA1 R.sub.5, R.sub.8 and R.sub.9 are the same or different and are selected from the group consisting of alkyl radicals of 1 to 4 carbons; PA1 in structure (5) and when T is a direct bond in structure (6), R.sub.6 and R.sub.7 are the same or different and are selected from the group consisting of H-- and alkyl radicals of 1 to 4 carbons; PA1 in structure (6) when T is oxy, R.sub.6 and R.sub.7 are the same or different and are selected from the group consisting of alkyl radicals of 1 to 4 carbons; PA1 R.sub.10 is selected from the group consisting of t-alkyl radicals of 4 to 12 carbons, t-aralkyl radicals of 9 to 13 carbons, t-alkynyl radicals of 5 to 9 carbons, and structures (7), (8), (9), (10), (11) and (12): ##STR9## where: R.sub.12 and R.sub.13 can be the same or different and are selected from the group consisting of H-- and alkyl radicals of 1 to 8 carbons; PA1 R.sub.14 is selected from the group consisting of H--, alkyl radicals of 1 to 8 carbons, alkenyl radicals of 2 to 8 carbons, aryl radicals of 6 to 10 carbons, alkoxy radicals of 1 to 6 carbons, and aryloxy radicals of 6 to 10 carbons; PA1 R.sub.13 and R.sub.14 may be concatenated to form an alkylene diradical of 4 to 5 carbons; PA1 R.sub.15 and R.sub.16 are independently selected from alkyl radicals of 1 to 4 carbons; PA1 R.sub.17 and R'.sub.17 are independently selected from the group consisting of H--, lower alkyl radicals of 1 to 4 carbons, alkoxy radicals of 1 to 4 carbons, phenyl radicals, acyloxy radicals of 2 to 8 carbons, t-alkylperoxycarbonyl radicals of 5 to 9 carbons, hydroxy, fluoro, chloro, and bromo; PA1 x is 0 or 1; PA1 R.sub.18 is selected from substituted or unsubstituted alkyl radicals of 1 to 18 carbons, substituents being one or more alkyl radicals of 1 to 6 carbons, t-alkylperoxy radicals of 4 to 8 carbons, alkoxy radicals of 1 to 6 carbons, aryloxy radicals of 6 to 10 carbons, hydroxy, chloro, bromo and cyano; substituted or unsubstituted cycloalkyl radicals of 5 to 12 carbons, substituted or unsubstituted saturated heterocycles of 5 to 12 atoms having an oxygen atom or a nitrogen atom in the heterocyclic ring with substituents for either cyclic radical being one or more lower alkyl radicals of 1 to 4 carbons, or R.sub.18 may optionally be the radical: ##STR10## where y is 0 or 1, R.sub.a, R.sub.b and R.sub.c are the same or different and are selected from H-- or alkyl radicals of 1 to 8 carbons, with the proviso that R.sub.a and R.sub.b may be concatenated to form a substituted or unsubstituted alkylene diradical of 4 to 11 carbons, with substituents being one or more alkyl radicals of 1 to 5 carbons or phenyl radicals; PA1 R.sub.19 is selected from the group consisting of alkyl radicals of 1 to 4 carbons and, additionally, the two R.sub.19 radicals may optionally be concatenated to form an alkylene diradical of 4 to 5 carbons; PA1 R.sub.11 is selected from the group consisting of unsubstituted alkylene diradicals of 2 to 3 carbons, alkylene diradicals of 2 to 3 carbons substituted with one or more alkyl radicals of 1 to 4 carbons, an unsubstituted 1,2-phenylene diradical, and 1,2-phenylene diradicals substituted with one or more lower alkyl radicals of 1 to 4 carbons, chloro, bromo, nitro or carboxy; and, PA1 X is a direct bond or is selected from the group consisting of connecting diradical structures (13), (14), (15) and (16): ##STR11## where (R--Q) shows the point of attachment of the R--Q group to the unsymmetrical X connecting diradical; PA1 z is 1 to 10; PA1 R.sub.22 is an alkylene diradical of 2 to 4 carbons, optionally substituted with one or more alkyl radicals of 1 to 4 carbons; and, PA1 when the X connecting diradical is structure (16), R.sub.1 may additionally be the peroxide containing radical of structure (17): ##STR12## PA1 a) curing unsaturated polyester resin substrates, PA1 b) polymerizing ethylenically unsaturated monomer substrates, PA1 c) crosslinking olefin polymer substrates, PA1 d) curing of elastomer substrates, PA1 e) modifying polyolefin substrates, PA1 f) grafting ethylenically unsaturated monomer substrates onto olefin homo- and copolymer substrates, and PA1 g) compatibilizing blends of two or more normally incompatible polymer substrates; which comprises heating said substrates in the presence of an amount effective for initiating the reaction to be performed of one or more peroxides of the first composition aspect of the invention for a time sufficient to at least partially decompose said peroxides of the first composition aspect of the invention. PA1 a) decomposing at least one peroxy polymer of the second composition aspect of the invention in the presence of a substrate selected from the group consisting of free radical poloymerizable monomers and free radical curable polymers to form a copolymer, PA1 b) incorporating a compatibilizing effective amount of the copolymer formed in step a above into a mixture of two or more otherwise incompatible polymers each member of which polymer mixture is compatible with at least one of the polymeric portions of said copolymer formed in step a.
The major problem encountered in developing new blends and alloys is the inherent incompatibility or immiscibility of almost all mixtures of two or more polymers. The consequence of incompatibility of polymeric blends and alloys is that they are unstable and, with sufficient time and temperature, form separate phases, thus, physical properties of the polymeric blends and alloys suffer. Generally, resin compounders have found that block and graft copolymers having polymeric segments that are compatible with the individual polymer components of blends and alloys enable formation of blends and alloys having enhanced phase stabilities and physical properties.
Low cost blends and alloys are commercially produced from two or more addition polymers such as blends involving low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and polypropylene (PP). The compatibility of these low cost blends can be improved by crosslinking with peroxides or by use of compatibilizing block or graft copolymers as mentioned above.
An important use of polymeric-peroxides such as polymers derived from the novel unsaturated peroxides of Structure A (as defined herein below) is their utility in preparing graft copolymers useful for compatibilizing polymeric blends and alloys. The polymeric-peroxides, derived from the novel unsaturated peroxides of Structure A of the instant invention, are effective in the preparation of graft copolymer compositions. Such graft copolymers have utility in compatibilizing polymer blends and alloys.
2. Discussion of Prior Art
U.S. Pat. No. 4,119,657 discloses OO-t-alkyl O-allyl and O-methallyl monoperoxycarbonates: ##STR1##
Later publications, Chem. Abstracts, 91, 58075y, abstracting Japanese kokai 79 47,790; Chem. Abstracts, 92, 129658z, abstracting Japanese kokai 79 132,695; Chem. Abstracts, 92, 130797a, abstracting Japanese kokai 79 142,239; and Chem. Abstracts, 93, 48080y, abstracting Japanese kokai 80 09636 disclose preparations of polymeric peroxides by copolymerizing these OO-t-alkyl O-allyl and O-methallyl monoperoxycarbonates with ethylenically unsaturated monomers and preparations of graft copolymers from the resulting polymeric peroxides. These peroxides and the polymeric peroxides derived from them are not covered by the novel unsaturated peroxides of Structure A and the corresponding novel polymeric-peroxides derived from the compositions of Structure A.
F. Strain, J. Am. Chem. Soc., 72, pp. 1254-1263 (1950) disclosed low temperature dialkyl peroxydicarbonates and reported the preparation of diallyl peroxydicarbonate, a peroxydicarbonate with allyl groups. Based on data in this paper the latter peroxydicarbonate was very hazardous and exploded.
Chem. Abstracts, 79, 6548n, abstracting Italian Patent 869,166 discloses unsaturated diperoxide compounds for vulcanization of ethylene-propylene rubber, such as 1-phenyl-3,3-di-(t-butylperoxy)-1-propene: ##STR2##
The latter is not expected to polymerize very readily owing to the presence of a substituent on each of the unsaturated carbons. The structures of this Italian Patent are not covered by Structure A of the instant invention.
U.S. Pat. No. 3,536,676 discloses di-t-alkyl diperoxyfumarates and the copolymerizations of these diperoxyfumarates with monomers such as styrene, vinyl acetate, vinyl chloride, acrylonitrile, methyl methacrylate and butadiene.
U.S. Pat. No. 3,763,112 discloses the preparations of di-t-alkyl diperoxyfumarate adducts (polymeric and non-polymeric) that are preparable via reaction of di-t-alkyl diperoxyfumarate with compounds possessing labile C--H bounds, in the presence or absence of conventional free-radical generators and or upon exposure to actinic light (visible, ultraviolet, etc.).
Chem Abstracts, 105(20), 173232s, abstracting Japanese Patent Application 84/209679 discloses various OO-t-alkyl O-alkyl monoperoxyfumarates and the use of these monoperoxyfumarates in the preparation of styrene polymers of enhanced moldability.
British Patent 1,041,088 discloses peroxide-containing copolymer compositions derived from ethylenically unsaturated monomers such as vinyl esters, esters of (meth)acrylic acid, vinyl chloride, acrylonitrile, butadiene, isoprene, acrylamide and vinyl ethers, and unsaturated peroxyesters such as t-butyl peroxymethacrylate, OO-t-butyl O-hydrogen monoperoxymaleate, OO-t-butyl O-butyl monoperoxymaleate, OO-t-butyl O-butyl monoperoxyfumarate and t-butyl peroxycinnamate. In the cases of the OO-t-alkyl O-hydrogen monoperoxy fumarates and the OO-t-alkyl O-hydrogen monoperoxymaleates, polymers produced from them are expected to react at elevated temperatures via non-radical reactions to form non-peroxidic polymers and t-alkyl hydroperoxides. t-Butyl peroxymethacrylate is difficult to prepare and is hazardous owing to very exothermic self polymerization/decomposition. t-Butyl peroxycinnamate does not homopolymerize nor copolymerize very readily with common polymerizable ethylenically unsaturated monomers.
U.S. Pat. No. 4,658,001 discloses polymerizable, ethylenically unsaturated monoperoxycarbonates of Structure Z. ##STR3## and copolymers derived therefrom. Peroxide compounds of Structure Z are not covered by the unsaturated peroxide compositions of Structure A.
U.S. Pat. No. 4,855,428 discloses triazine peroxides possessing at least one carbon-carbon double bond, for instance, 2-t-amylperoxy-4,6-dialloxy-1,3,5-triazine, which are useful for crosslinking polymers and copolymers derived from ethylene. These compositions are not covered by Structure A of the instant invention and are not expected to polymerize very readily.
U.S. Pat. No. 4,129,700, U.S. Pat. No. 4,180,518, and U.S. Pat. No. 4,218,548 claim peroxides of the general formula: ##STR4## where R.sub.1 is hydrogen or an alkyl radical of 1 to 4 carbons, R.sub.2 and R.sub.3 are alkyl radicals of 1 to 4 carbons, R.sub.4 is a t-alkyl radical of 4 to 8 carbons, and Z is, ##STR5## where R.sub.5 and R.sub.7 are alkyl radicals of 1 to 8 carbons, R.sub.6 and R.sub.8 are hydrogen, alkyl radicals of 1 to 8 carbons, cycloalkyl radicals of 5 to 6 carbons, phenyl radicals, or alkylphenyl radicals of 7 to 10 carbons, and where D is an ethynyl diradical, a diethynyl diradical, or an alkyl diradical having 1 to 8 carbons. An example of a peroxide covered under these patents would be the reaction product of 2-(t-butylperoxy)-2-methyl-4-hydroxypentane with cyclohexyl isocyanate. This compound does not have a pendent polymerizable vinyl group. Moreover, as can be seen from the general structure given by these patents, in no case is there a compound claimed with a pendent polymerizable vinyl group as described by our general formula. However, another compound, whose synthesis is described in all three patents but which is not claimed, is the reaction product of allyl amine and 2-(t-butylperoxy)-2-methyl-4-chlorocarbonyloxypentane, i.e., N-allyl-O-[2-(t-butylperoxy)-2-methyl-4-pentyl]carbamate. Although this peroxide contains an allyl group, it is outside the scope of our invention as described by our general formula, because for the above carbamate to be covered by the instant invention --X-- would have to be the connecting diradical, --CH.sub.2 NH--. This connecting diradical is not one of the definitions for --X-- of Structure A.
U.S. Pat. No. 3,671,651 and U.S. Pat. No. 4,304,882 broadly disclose polymers with attached peroxide groups. However, these peroxy polymers were produced by the reaction of a peroxychloroformate such as 2-(t-butylperoxy)-2-methyl-4-chlorocarbonyloxypentane and a hydroxy containing polymer such as a polyether diol (for example, Carbowax.TM. produced by the Union Carbide Corp.). In general, U.S. Pat. No. 3,671,651 teaches that a peroxide with an acylating functionality such as an acid chloride or a chloroformate can react with polymers containing terminal or pendent hydroxyl, amino, and mercapto groups or any other functionality that can be acylated. This patent specifically claims peroxy polymers in which the peroxide is attached to the polymer by either an ester or a carbonate group (i.e. connecting groups), there is no claim of either an amide, a carbamate, or a urea as connecting groups which by definition are part of general structure A of our invention. Moreover, there is no mention that peroxy polymers can be prepared by copolymerization with a peroxy monomer. Therefore, the peroxy polymers of U.S. Pat. No. 3,671,651 are outside the scope of this invention. U.S. Pat. No. 4,304,882 also teaches that peroxides with acylating functionalities can react with polymers containing terminal or pendent hydroxyl, amino, or mercapto groups to form peroxy polymers. In this case amide and carbamate groups are specifically claimed as connecting groups linking the peroxide moiety to the polymer backbone. However, there is no mention of vinyl group containing peroxy monomers being copolymerized with other monomers or of the peroxide being part of the repeat unit(s) in the polymer backbone. In addition there is a difference in the general formulas for this patent and our invention. The general formula for the peroxy polymers of U.S. Pat. No. 4,304,882 is as follows: EQU [(A.sub.n1 --R--D.sub.n2).sub.v P.sub.n3 ].sub.v Z.sub.n4
where: n1, n2, n3, n4, v, and w are integers; A defines a peroxide moiety; R is a di-, tri-, or tetra valent hydrocarbon radical; D is an ester, carbonate, amide, carbamate, etc. connecting group; P is a polyvalent residue of a polymer less its terminal and pendent Z and (A.sub.n1 --R--D.sub.n2) groups; and Z is --H, --OH, --NH.sub.2, etc. Thus, in the case of the general formula in U.S. Pat. No. 4,304,882, the --R--D-- group connects the peroxide unit, A--, to the polymer backbone. In the general formula A for the compositions of the instant invention the connecting group between the polymer backbone and the peroxide group, --R.sub.1, is --X--. The definitions of --X-- are different than those of --R--D. For instance, in the case of the peroxy-polymers of U.S. Pat. No. 4,304,882, the connecting group of atoms to the polymer backbone is either --O--(P)--, --NH--(P)--, --NR.sub.2 --(P)-- or --S--(P)-- [Where (P) is a polymer backbone of U.S. Pat. No. 4,304,882.]. In the case of the instant invention the connecting group of atoms to the polymer backbone is either one or more carbon atoms, --C(O)--(P')-- or --O--C(O)--(P')-- [where (P') is a polymer backbone of the instant invention.] Thus, in the instant invention the peroxide is attached to the polymer backbone by quite different connecting groups.
U.S. Pat. No. 5,011,981 discloses the reaction products of methacryloyl isocyanate and hydroperoxides. A typical example is the reaction of t-butyl hydroperoxide with methacryloyl isocyanate to yield a peroxycarbamate with the following proposed structure: ##STR6## Although this is a polymerizable peroxide, it is outside the scope of our invention, because for it to be included in our invention, --X-- of our general structure would have to be the connecting diradical, --C(O)--NH--. This connecting diradical is not included in the definition of --X--.